Nowadays, most chemical analysis methods require the stirring of samples to obtain a proper homogenization, fluidization or mixing of all the substances in that sample, or to carry out extraction processes of some of the constituents of the sample. Stirring apparatuses currently used perform orbital stirring, rotational stirring, vibration stirring, swinging stirring, magnetic stirring, propeller stirring and pendular stirring.
Orbital stirring (WO86/00995, US005558437A) consists of making the sample follow a circular or elliptical orbit and selecting its frequency, that is to say, the number of complete orbits per second.
Rotational stirring (ES188622) consists of rotating the sample on an imaginary rotation axis which contains it.
Vibration or vortex stirring (ES2160401T3), (U.S. Pat. No. 4,883,644, U.S. Pat. No. 4,305,668, US2005/0180258) is generated through an orbital stirrer-like movement with high frequency, having said stirrer a very small orbit radius (usually less than 1 centimeter) thus generating the vibration transmitted by direct contact on the container base containing the sample.
Swinging stirring or swaying movement (ES219812Y) consists of making a platform oscillate alternately around an axis containing said platform. The containers which carry the sample are placed on this platform so that they perform this swaying movement.
Propeller stirring (ES2039656, US005141327A) consists of placing in the container with the sample a rod on whose end there is a propeller. The other end of the rod is connected to a rotating motor which makes it rotate, thus stirring the sample.
Magnetic stirring (ES2064649, DE202004013715U1, GB1180278, US2005088912, EP1188474) consists of placing in the container with the sample a cylinder-like, small, encapsulated magnet (so that it does not chemically react when in contact with the samples). A rotating magnetic field is generated below the container, making the magnet in the container spin at the same frequency as the rotating field does.
Pendular stirring (ES251833Y) consists of attaching the sample to a rod whose opposite end moves in an oscillating way, emulating the movement of a pendulum.
There exist some processes (chemical analyses, production of mixtures, extraction processes, etc.) in which the application of the previously described apparatuses does not produce an adequate homogenization and/or extraction of the stirred substances. In such cases the application of an axially oscillating movement is required, be it vertical, horizontal or with any other inclination between both options. From the countless axial orientations the oscillation can have, we have selected the vertical movement as an example thereof, without limiting the scope of this invention, which is defined exclusively by the claims. That is to say, when referring to oscillating vertical stirring, the sample must go up and down on a balance position, with a certain frequency and amplitude.
Nowadays, this vertical stirring movement is performed manually, which causes reproducibility and repeatability problems. The problem is even more noticeable when a large number of samples have to be stirred simultaneously.
Neither in the market nor in the consulted bibliography is there a system, apparatus, instrument or method which facilitates the performance of this oscillating vertical stirring in an automated way.
The invention hereby described solves the aforementioned problems as it is capable of stirring several samples jointly or individually and enabling to select the basic parameters of vertical stirring, which are: oscillation amplitude, oscillation frequency, acceleration, deceleration, and application time of the stirring effect as well as selection of stirring and rest cycles.